Image reading device and image reading method

ABSTRACT

A technology capable of preventing generation of a problem due to saturation of an output value in an image pick-up section caused by a variation of illumination light from a light source. An image reading device includes a plurality of light sources each of which illuminates a document surface as a target for reading with illuminating light of a color different from the other light sources, an image pick-up section for imaging light radiated from the plurality of the light sources and reflected on the document surface, a controlling unit for making the plurality of the light sources emit light with any one of the plurality of the light sources as a reference light source, and an adjusting unit for lowering a current value of a power source which makes the reference light source emit light when an amount of light imaged in the image pick-up section exceeds a threshold value as a predetermined upper limit value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority from and is aContinuation of application Ser. No. 11/743,235 filed on May 2, 2007,which claims the benefit of priority from Japanese patent applicationNo. 2006-129841 filed on May 9, 2006, the entire contents of both ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image reading device, and atechnique of preventing saturation of an output value of an imagepick-up section in a case of imaging light radiated by a light sourceand reflected from a document surface.

2. Description of the Related Art

An image reading device using three colors of LEDs, a red LED, a blueLED, and green LED, for a light source as a means for illuminating adocument is conventionally known. In the image reading device of aconfiguration such as above, as a means for controlling a light amountof each of the red LED, the blue LED, and the green LED, a technique ofhaving any one of the LEDs of the red LED, the blue LED, and the greenLED as a reference light source, and controlling the light amount of theother two LEDs with the light amount of the reference light source as areference, is known.

However, an LED has many variations in a light amount as compared withother light sources such as a xenon lamp. In a case of the conventionalimage reading device described above, when there is a variation in thelight amount of the reference LED (reference light amount) among the redLED, the blue LED, and the green LED, a light amount as an entire lightsource is significantly different between the reference LED having amaximum reference light amount and the reference LED having a minimumreference light amount. For example, in a case of the reference LEDhaving the maximum reference light amount, a range of an amount of lightwhich can be detected in an image pick-up section (for example, a CCD)is exceeded, and this causes a problem that an output value in the imagepick-up section is saturated (data of the amount exceeding the range islost).

SUMMARY OF THE INVENTION

An object of an embodiment of the present invention is to provide atechnique capable of preventing generation of the problem due tosaturation of an output value in the image pick-up section caused by avariation of light illuminated from a light source.

In order to achieve the above object, according to an aspect of thepresent invention, there is provided an image reading device comprising:a plurality of light sources each of which illuminates a documentsurface as a target for reading with illuminating light of a colordifferent from the other light sources; an image pick-up section thatimages light radiated from the plurality of the light sources andreflected on the document surface; a controlling unit that makes theplurality of the light sources emit light with any one of the pluralityof the light sources as a reference light source so that light amountsof the light sources other than the reference light source are in apredetermined ratio with respect to a light amount of the referencelight source; and an adjusting unit that lowers a current value of apower source which makes the reference light source emit light when anamount of light imaged in the image pick-up section exceeds a thresholdvalue as a predetermined upper limit value at the time only thereference light source illuminates a predetermined reference surface, sothat the amount of light imaged in the image pick-up section is equal toor smaller than the threshold value.

In addition, according to an aspect of the present invention, there isprovided an image reading device comprising: a plurality of lightsources each of which illuminates a document surface as a target forreading with illuminating light of a color different from the otherlight sources; an image pick-up section that images light radiated fromthe plurality of the light sources and reflected on the documentsurface; a controlling unit that makes the plurality of the lightsources emit light with any one of the plurality of the light sources asa reference light source so that light amounts of the light sourcesother than the reference light source are in a predetermined ratio withrespect to a light amount of the reference light source; and anadjusting unit that raises light receiving sensitivity of the imagepick-up section when an amount of light imaged in the image pick-upsection is lower than a threshold value as a predetermined lower limitvalue at the time only the reference light source illuminates apredetermined reference surface, so that the amount of light imaged inthe image pick-up section is equal to or larger than the thresholdvalue.

In addition, according to an aspect of the present invention, there isprovided an image processing apparatus comprising an image readingdevice of a configuration as described above and an image forming unitthat forms an image on a sheet of paper based on image data of thedocument read by the image reading device.

In addition, according to an aspect of the present invention, there isprovided an image reading method in an image reading device that imageslight radiated from a plurality of light sources, each of which isilluminating light of a color different from the other light sources,and reflected on a document surface as a target for reading, comprising:lowering a current value of a power source which makes the referencelight source emit light when an amount of light imaged in the imagepick-up section exceeds a threshold value as a predetermined upper limitvalue at the time any one of the plurality of the light sources works asa reference light source and only the reference light source illuminatesa predetermined reference surface, so that the amount of light imaged inthe image pick-up section is equal to or smaller than the thresholdvalue; and controlling light emission of the plurality of the lightsources so that light amounts of the light sources other than thereference light source are in a predetermined ratio with respect to thelight amount of the reference light source.

In addition, according to an aspect of the present invention, there isprovided an image reading method in an image reading device that imageslight radiated from a plurality of light sources, each of which isilluminating light of a color different from the other light sources,and reflected on a document surface as a target for reading, comprising:raising light receiving sensitivity at the time of imaging in the imagereading device with any one of the plurality of the light sources as areference light source when an amount of light imaged in the imagepick-up section is lower than a threshold value as a predetermined lowerlimit value at the time only the reference light source illuminates apredetermined reference surface, so that the amount of light imaged isequal to or larger than the threshold value; and controlling lightemission of the plurality of the light sources so that light amounts ofthe light sources other than the reference light source are in apredetermined ratio with respect to the light amount of the referencelight source.

In addition, according to an aspect of the present invention, there isprovided an image reading device comprising: a plurality of lightsources each of which illuminates a document surface as a target forreading with illuminating light of a color different from the otherlight sources; an imaging means for imaging light radiated from theplurality of the light sources and reflected on the document surface; acontrolling means for making the plurality of the light sources emitlight with any one of the plurality of the light sources as a referencelight source so that light amounts of the light sources other than thereference light source are in a predetermined ratio with respect to alight amount of the reference light source; and an adjusting means forlowering a current value of a power source which makes the referencelight source emit light when an amount of light imaged in the imagingmeans at the time only the reference light source illuminates apredetermined reference surface exceeds a threshold value as apredetermined upper limit value, so that the amount of light imaged inthe imaging means is equal to or smaller than the threshold value.

In addition, according to an aspect of the present invention, there isprovided an image reading device comprising: a plurality of lightsources each of which illuminates a document surface as a target forreading with illuminating light of a color different from the otherlight sources; an imaging means for imaging light radiated from theplurality of the light sources and reflected on the document surface; acontrolling means for making the plurality of the light sources emitlight with any one of the plurality of the light sources as a referencelight source so that light amounts of the light sources other than thereference light source are in a predetermined ratio with respect to alight amount of the reference light source; and an adjusting means forraising light receiving sensitivity of the imaging means when an amountof light imaged in the imaging means at the time only the referencelight source illuminates a predetermined reference surface is lower thana threshold value as a predetermined lower limit value, so that theamount of light imaged in the imaging means is equal to or larger thanthe threshold value.

In addition, according to an aspect of the present invention, there isprovided an image processing apparatus comprising an image readingdevice of a configuration as described above and an image forming meansfor forming an image on a sheet of paper based on image data of thedocument read by the image reading device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an entire configuration diagram for explaining an imagereading device according to the present embodiment and an imageprocessing apparatus including the image reading device;

FIG. 2 is a configuration diagram showing a detail of a CIS 120(carriage) in an image reading device 1 according to the presentinvention;

FIG. 3 is a functional block diagram for explaining the image readingdevice according to the present invention;

FIG. 4 is a view for explaining adjustment of a gain of a CCD output;

FIG. 5 is a view for explaining the adjustment of a gain of the CCDoutput;

FIG. 6 is a flowchart for explaining control of a light amount of a redLED;

FIG. 7 is a flowchart for explaining control of a light amount of thered LED;

FIG. 8 is a flowchart for explaining control of a light amount of a blueLED;

FIG. 9 is a flowchart for explaining control of a light amount of ayellow-green LED;

FIG. 10 is a view showing a drive circuit of a green LED;

FIG. 11 is a view for explaining an advantageous effect of the presentinvention; and

FIG. 12 is a flowchart for explaining a general flow of processing inthe image reading device according to the present invention (imagereading method).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the present invention will be describedwith reference to the accompanying drawings.

FIG. 1 is an entire configuration view for explaining an image readingdevice according to the present invention and an image processingapparatus including the image reading device. An image reading device 1according to the present embodiment is mounted in the image processingapparatus (MFP, Multi Function Peripheral) M as shown in FIG. 1.

The image processing apparatus M shown in FIG. 1 is configured toinclude the image reading device 1 and an image forming device (imageforming unit) 2. The image forming device 2 is capable of carrying outimage forming processing (print processing, copy processing, etc.) to asheet of paper based on image data received by an external equipment andimage data read from a document by the image reading device 1.

The image reading device 1 is capable of manual reading in which animage of a document placed on a document table glass 109 is read bymoving a CIS (Contact Image Sensor) 120 including an optical system andan image pick-up section for imaging a light source illuminating thedocument and reflected light from a document surface illuminated by thelight source in a predetermined direction R. The image reading device 1is also capable of an ADF reading in which the image of the documentmoving in an F direction (conveyed by an ADF (Auto Document Feeder)) isread by the CIS 120 static at a predetermined position P.

FIG. 2 is a configuration view showing a detail of the CIS 120(carriage) in the image reading device 1 according to the presentembodiment. As shown in FIG. 2, the CIS 120 includes a firstillumination unit 121, a second illumination unit 122, an optical system125, and an image pick-up section 126. In addition, the image processingapparatus M includes a CPU 801 and a MEMORY 802 used in the imagereading device 1 and the image forming device 2.

The first illumination unit 121 is configured with a light transmissiontube of a white type including three LEDs, a red LED, a green LED, and ablue LED, as a light source. The first illumination unit 121 illuminatesa document surface from a direction inclining toward the documentsurface for a predetermined angle.

The second illumination unit 122 is configured with a LED arrayincluding a yellow-green LED as a light source and has a spectralcharacteristic different from the first illumination unit. The secondillumination unit 122 illuminates the document surface from a directionsubstantially symmetrical to the first illumination unit with respect toa normal line to the document surface. As described above, the documentsurface is illuminated from two positions line symmetrical to each otherwith illumination light of colors different from each other. Thereby, aread image without a shadow can be obtained regardless of existence ofirregularities on the document surface. As described above, a pluralityof the light sources in the image reading device according to thepresent embodiment include at least any of the red LED, the green LED,the blue LED, and the yellow-green LED.

The optical system 125 is configured with a Selfoc lens, etc. Theoptical system 125 leads light radiated from the first illumination unit121 and the second illumination unit 122 and reflected by the documentsurface (refer to an arrow directed in a downward direction in FIG. 2)to a predetermined image formation position. Here, an example where theoptical system 125 is entirely arranged on the CIS 120 is shown.

The image pick-up section 126 is configured with a photoelectricconversion element, etc. and images the light led to the predeterminedimage formation position by the optical system 125. Here, the imagepick-up section 126 is assumed to be a CCD. An image of a documentimaged by the image pick-up section 126 is stored in the MEMORY 802, andis transmitted to an external equipment which can communicate with theimage forming device 2 or the image processing apparatus M as needed.The CIS 120 with a configuration such as above is driven in an Rdirection by a drive belt 108.

FIG. 3 is a functional block diagram for explaining the image readingdevice according to the present embodiment. As shown in FIG. 3, theimage reading device 1 according to the present embodiment is configuredto include a plurality of light sources, a controlling unit (controllingmeans) 101, an adjusting unit (adjusting means) 102, the image pick-upsection 126, the CPU 801, and the MEMORY 802.

The controlling unit 101 makes the plurality of the light sources emitlight in a manner that, when any one of the plurality of the lightsources is a reference light source, light amounts of the light sourcesother than the reference light source are in a predetermined ratio withrespect to a light amount of the reference light source. Morespecifically, the controlling unit 101 has the light source with thehighest output value among the plurality of the light sourcesconstituting the first illumination unit 121 and the second illuminationunit 122 (here, the green LED constituting the first illumination unit121) as the reference light source, and adjusts output values of theother light sources by a D/A converter. Thereby, the controlling unit101 makes each of the LEDs emit light so that the light amounts of thelight sources other than the reference light source (red LED, blue LED,and yellow-green LED) are, for example, in the following ratio withrespect to the light amount of the green LED:amount of light of redLED:amount of light of green LED:amount of light of blue LED:amount oflight of yellow-green LED=0.26:1.0:0.22:1.02.

The adjusting unit 102 lowers a current value of a power source whichmakes the reference light source emit light when an amount of lightimaged by the image pick-up section 126 exceeds a threshold value as apredetermined upper limit value at the time only the reference lightsource illuminates a predetermined reference surface (equivalent to ashading correction plate ((white reference plate) shown in FIG. 2), sothat the amount of light imaged by the image pick-up section 126 becomesequal to or smaller than the threshold value. More specifically, theadjusting unit 102 adjusts the current value of the power sourcesupplied to the green LED to be, for example, around ½ by using the D/Aconverter.

On the other hand, the adjusting unit 102 raises light receivingsensitivity of the image pick-up section 126 when the amount of lightimaged by the image pick-up section 126 is smaller than a thresholdvalue as a predetermined lower limit value, so that the amount of lightimaged by the image pick-up section 126 becomes equal to or larger thanthe threshold value.

The CPU 801 has a role of carrying out a variety of types of processingin the image reading device 1 and the image processing apparatus M. Inaddition, the CPU 801 has a role of achieving a variety of functions byexecuting a program stored in the MEMORY 802. The MEMORY 802 isconfigured with, for example, a ROM, a RAM, etc., and has a role ofstoring a variety of types of information and programs used in the imagereading device 1 and the image processing apparatus M.

As in the present embodiment, when the LED is used as an illuminatingmeans, a light amount of the LED sometimes changes due to a variation ofcharacteristics between each product and deterioration with age of theLED. The change of the light amount of the LED as described above causesa difference in density of image reading in each image reading device.In order to prevent the problem, the light amount of each of the LEDs isoptimized at the time of activation and image adjusting of the imagereading device 1 to prevent generation of a difference in density ofimage reading. FIGS. 4 to 9 are flowcharts showing a flow of processingof optimizing the light amount of each of the LEDs in the image readingdevice 1 according to the present embodiment.

In the image reading device 1 according to the present embodiment, thelight amount of the green LED which is the reference light source is notcontrolled, and a gain of a CCD output is adjusted based only on thelight amount of the reference light source. Thereafter, the lightamounts of the red, blue, and yellow-green LEDs are controlled. Detailsthereof will be described hereinafter.

First, the adjustment of a gain of the CCD output will be described byusing FIGS. 4 and 5. At activation of the image reading device, thecarriage is moved to a white reference detecting position which is areference color (S101). In this state, only the reference light source(for example, the green LED) is first lighted (S102) and light in theLEDs other than the green LED is turned off (S103). At this time, peakdetection data MaxA to MaxD and a threshold value 6 (corresponding to athreshold value as an upper limit value) are compared (S104 to S108). Ifthe MaxA to MaxD is equal to or larger than the threshold value 6 (S108,Yes), the light amount of the green LED is too large and error occurs,and the user is notified of abnormality in the light source by a servicecall (S109). If the MaxA to MaxD is smaller than the threshold value 6(S108, No), peak detection starts (S110). The peak detection is anoperation of optimizing the CCD output at the white reference detectingposition (position P in FIG. 1). In addition, since the CIS isconfigured with four channels, the peak detection data MaxA to MaxD isthe maximum value of the CCD output of each channel.

After the peak detection starts, a gain of the CCD output is increaseduntil the MaxA to MaxD is equal to or larger than a threshold value 5(S110 to S117). This operation is repeated, and if the MaxA to MaxD doesnot become equal to or larger than the threshold value 5 (correspondingto a threshold value as a lower limit value) even when the gain israised to the maximum value (S114, Yes), the light amount cannot beadjusted. Then, the user is notified of abnormality of the light sourceby a service call (S119). If the MaxA to MaxD is equal to or larger thanthe threshold value 5 (S115, No), the gain of the CCD output isconsidered to have been adjusted, and the control of the light amount ofthe green LED is terminated. At this time, the maximum value of the gainof a previous processing register is extracted, and a gain adjustedvalue is written in a register G_LED_MAX_CH (S115, S116).

After the adjustment of the gain of the CCD output, control of the lightamount of the red LED is carried out as shown in FIGS. 6 and 7. First,only the red LED is lighted (S201), and light in the other LEDs isturned off. In this state, the adjusted value of the gain of the CCDoutput is read from the register, and the gain is set (S202 to S205).The CCD output at this time and the threshold values 7 and 8 arecompared (S206), and if the CCD output is smaller than a threshold 7, avalue of FFEB14H which is a setting value of a voltage of the red LED isincreased by the D/A converter. Again, comparison between the thresholdvalue 7 and the CCD output is repeated (S209 to S215). If the CCD outputdoes not become equal to or larger than the threshold value 7 even whenthe operation is repeated until the maximum value of the FFEB14H, theuser is notified of abnormality in the light source by a service call(S211, S212). If the CCD output is larger than a threshold value 8, thevalue of the FFEB14H is lowered in order to lower the CCD output. Again,the comparison between the threshold value 7 and the CCD output isrepeated (S207 to S215). If the CCD output does not become equal to orsmaller than the threshold value 8 even when the operation is repeateduntil the minimum value of the FFEB14H, the user is notified ofabnormality in the light source by a service call (S211, S212). In thismanner, when the CCD output is equal to or larger than the thresholdvalue 7 and equal to or smaller than the threshold value 8, a value ofFFEB10H at that time is written in an NVRAM (S213, S214).

FIG. 8 is a flowchart for explaining control of a light amount of theblue LED. Since processing in FIG. 8 (S301 to S315) is similar to thecontent of the processing of the control of the light amount of the redLED (S201 to S215), a detailed explanation thereof is omitted. In theprocessing shown in FIG. 8, a value of an FFB18H is adjusted so that theCCD output is equal to or larger than a threshold value 9 and equal toor smaller than a threshold value 10. After the adjustment, the value iswritten in the NVRAM.

FIG. 9 is a flowchart for explaining control of a light amount of theyellow-green LED. Since processing in FIG. 9 (S401 to S415) is alsosimilar to the content of the processing of the control of the lightamount of the red LED (S201 to S215), a detailed explanation thereof isomitted. In the processing shown in FIG. 9, a value of an FFB14H isadjusted so that the CCD output is equal to or larger than a thresholdvalue 11 and equal to or smaller than a threshold value 12. After theadjustment, the value is written in the NVRAM.

As described above, the light amounts of the red, blue, and yellow-greenLEDs are adjusted, and then the peak detection is carried out to adjusta gain of the CCD output.

In the present embodiment, the threshold values 5 to 12 shown in theflowcharts described above are as follows:

threshold value 5—97;

threshold value 6—102;

threshold value 7—24;

threshold value 8—27;

threshold value 9—20;

threshold value 10—23;

threshold value 11—100; and

threshold value 12—105.

In addition, the values of the threshold values 5 to 12 are set so as tohave a ratio of the light amounts of the green LED, the red LED, theblue LED, and the yellow-green LED equal to the ratio described above.

By carrying out the control of the light amount as described above, whenimage reading of a document is carried out by the image reading device1, the image reading can constantly be carried out with an optimizedlight amount by reading set values of the light amounts of the red,blue, and yellow-green LEDs written in the NVRAM.

In a case where there is a variation in the light amount of the greenLED which is the reference light source, that is, in a case of an LEDwhere the light amount of the reference light source is a maximum valuein a range of a variation, the light amount is equal to or larger thanthe threshold 6 as shown in FIGS. 4 and 5, and the CCD output issaturated. Therefore, by inputting in a green LED drive circuit shown inFIG. 10 by switching over 5 V and 0 V, current to the green LED can beswitched to be multiplied by one or ½. In the flowcharts shown in FIGS.4 and 5, if the CCD output is equal to or larger than the thresholdvalue 6, by inputting in the above drive circuit by switching 5 V and 0V, the current to the green LED can be multiplied by ½, and the lightamount of the green LED can be reduced to half.

As shown in FIG. 11, in conventional art, when a light amount iscontrolled by a light amount maximum product (product which has amaximum value of a light amount in a variation of the light amount), theCCD output has been saturated. However, by using the control of a lightamount in the present invention, an appropriate amount of light by whichthe CCD output is not saturated can be set in either the light amountmaximum product and a light amount minimum product (product which has aminimum value of a light amount in a variation of the light amount).

FIG. 12 is a flowchart for explaining a general flow of processing inthe image reading device according to the present embodiment (imagereading method).

First, the image pick-up section 126 images light radiated from aplurality of the light sources (red LED, green LED, blue LED, andyellow-green LED) each of which is illumination light of colorsdifferent from one another and reflected by the document surface whichis a target of reading (imaging step) (S501).

Next, the adjusting unit 102 lowers a current value of a power sourcewhich makes the reference light source emit light when an amount oflight imaged in the imaging step exceeds a threshold value as apredetermined upper limit value at the time any one of a plurality ofthe light sources works as the reference light source and only thereference light source illuminates a predetermined reference surface(S502, Yes), so that the amount of light imaged in the imaging stepbecomes equal to or smaller than the threshold value (adjusting step)(S503). On the other hand, the adjusting unit 102 raises light receivingsensitivity of the image pick-up section 126 when the amount of lightimaged in the imaging step is lower than a threshold value as apredetermined lower limit value (S504, Yes), so that the amount of lightimaged by the image pick-up section 126 becomes equal to or larger thanthe threshold value (adjusting step) (S505).

The controlling unit 101 makes the plurality of the light sources emitlight in a manner that, with any one of the plurality of the lightsources is a reference light source, light amounts of the light sourcesother than the reference light source are in a predetermined ratio withrespect to a light amount of the reference light source (controllingstep) (S506).

Each of the steps in the processing in the image reading devicedescribed above is achieved by making the CPU 801 execute an imagereading program stored in the MEMORY 802.

In the present embodiment, a case in which a function of carrying outthe invention is recorded inside the device in advance has beendescribed. The present invention is not limited thereto, and a similarfunction may be downloaded from a network to the device. Alternatively,a similar function which is stored in a recording medium may beinstalled to the device. As the recording medium, a form of therecording medium may be any form if the recording medium can store aprogram and is one from which the device can read, such as a CD-ROM. Inaddition, a function which is obtained by installing or downloading inadvance as described above may work in association with an OS (operatingsystem), etc. inside the device to achieve the function.

As described above, according to the present invention, saturation ofthe CCD output can be prevented in a case of using an illuminatingdevice having many variations in an amount of light such as an LED as alight source, and a stabilized CCD output can be obtained.

The present invention has been described in detail with a specificembodiment. However, it is obvious to one skilled in the art that avariety of changes and modifications can be made without deviating fromthe spirit and the scope of the present invention.

1. An image reading device comprising: a conveying unit that conveys adocument to a document reading position; a first light emitting elementthat is disposed at an upstream side of the document reading position ina direction in which the document is conveyed, and emits light to thedocument at the document reading position; a second light emittingelement that is disposed at a downstream side of the document readingposition in the document conveying direction, and emits light differentin color from the light emitted by the first light emitting element tothe document at the document reading position; a photoelectrictransducer; and an optical member that guides light reflected from thedocument at the document reading position to the photoelectrictransducer.
 2. The image reading device according to claim 1, whereinthe first and second light emitting elements are disposed at locationssymmetric to each other with respect to the document reading position.3. The image reading device according to claim 1, wherein the firstlight emitting element comprises a red LED, a green LED, and a blue LED.4. The image reading device according to claim 1, wherein the secondlight emitting element comprises a yellowish-green LED.
 5. The imagereading device according to claim 1, wherein the first light emittingelement comprises a yellowish-green LED.
 6. The image reading deviceaccording to claim 1, wherein the second light emitting elementcomprises a red LED, a green LED, and a blue LED.
 7. The image readingdevice according to claim 1, wherein the optical member comprises aSelfoc lens.
 8. An image reading device comprising: an exposure unitthat has a plurality of light sources and is movable in a firstdirection; a first light emitting element that is disposed at anupstream side of a document reading position in the first direction, andemits light to the document at the document reading position; a secondlight emitting element that is disposed at a downstream side of thedocument reading position in the first direction, and emits lightdifferent in color from the light emitted by the first light emittingelement to the document at the document reading position; aphotoelectric transducer; and an optical member that guides lightreflected from the document at the document reading position to thephotoelectric transducer.
 9. The image reading device according to claim8, wherein the first and second light emitting elements are disposed atlocations symmetric to each other with respect to the document readingposition.
 10. The image reading device according to claim 8, wherein thefirst light emitting element comprises a red LED, a green LED, and ablue LED.
 11. The image reading device according to claim 8, wherein thesecond light emitting element comprises a yellowish-green LED.
 12. Theimage reading device according to claim 8, wherein the first lightemitting element comprises a yellowish-green LED.
 13. The image readingdevice according to claim 8, wherein the second light emitting elementcomprises a red LED, a green LED, and a blue LED.
 14. The image readingdevice according to claim 8, wherein the optical member comprises aSelfoc lens.